The present invention generally relates to the configuration management of a storage device, and more particularly to a data migration control method for a storage device.
In recent years, the volume of data used by corporations and individuals has increased dramatically. Therefore storage systems that use technology such as Storage Area Networks (SAN) or Network Attached Storage (NAS) that enable flexible data management by connecting storage sub-systems and host computers via switches or hubs have become widely used.
Also, in recent years reducing the operating cost of storage devices (hereafter, also referred to as storage sub-systems) has been an important task for the management of storage systems. Data life cycle management, in which data is relocated from, for example, a new storage sub-system to an older storage sub-system in accordance with how new the data is or the frequency of use of the data, has become important as one method for solving this task (the group of data relocation source and data relocation destination storage sub-systems is referred to as a storage tier).
One technology for achieving data life cycle management is technology for migrating the contents of a storage area (hereafter referred to as “volume”) of a storage sub-system to another volume without affecting the host computer that uses the volume.
Methods for carrying out migration include, for example, the methods disclosed in Japanese Patent Application Laid-open No. 2000-293317, U.S. Pat. No. 6,108,748, and Japanese Patent Application Laid-open No. 2003-345522. In these methods, first data is copied from a certain volume to another volume, and the data in the copy source is deleted. Address management of the copy source and copy destination is processed by an address management program. If the address is accessed from a host computer during data migration, an access processing program provides the host with data at an address managed by the address management program in the event of a read request. In the event of a write request, the data written to cache memory is retained, and later the data is written to the volume at the migration destination. By using the above processes, it is possible to interchange volumes. The data migration destination can be a volume within the same storage sub-system (see Japanese Patent Application Laid-open No. 2000-293317), a volume in a different storage sub-system (see U.S. Pat. No. 6,108,748), or volumes in different storage sub-systems managed as a single virtual storage sub-system (see Japanese Patent Application Laid-open No. 2003-345522).
Also, in Japanese Patent Application Laid-open No. 2003-067187, a method of automatically migrating data based on the logical volume performance information and the input/output (I/O) access frequency is disclosed. Also, in Japanese Patent Application Laid-open No. 2007-066259, a method of migrating data in units of the segments that constitute a logical volume in accordance with the frequency of I/O access to the logical volume from host computers is disclosed.